By virtue of such advantageous features as light weight, small thickness and low power consumption, flat-panel display devices, such as an organic electroluminescence (EL) display device and a liquid crystal display device, have been used in various fields of OA (office automation) equipment, information terminals, timepieces, and television receivers. In particular, by virtue of high responsivity, display devices using thin-film transistors (TFTs) are widely used as monitors of mobile terminals, computers, etc., which display a great deal of information.
In recent years, as regards mobile information terminal devices such as mobile phones and PDAs (personal digital assistants), there has been an increasing demand for a display device having a less thickness and a less weight, from the standpoint of design and portability, as well as performance. For example, display devices, which realize thinner structures, have been proposed. As a method of realizing a less thickness and less weight, there is known a technique wherein a resin layer formed of a polyimide with a relatively high heat resistance, or a plastic substrate, is used in place of a glass substrate. When a resin layer is formed of a polyimide, a resin layer using a polyimide is formed on a glass substrate. After TFTs, etc. are formed on the resin layer, the resultant structure is divided into cells, and at last the resin layer is peeled from the glass substrate. Thereby, the resin layer can be formed.